title: A carbon monoxide-releasing molecule (CORM-3) uncouples mitochondrial respiration and modulates the production of reactive oxygen species.
abstract: Carbon monoxide (CO), produced during the degradation of heme by the enzyme heme oxygenase, is an important signaling mediator in mammalian cells. Here we show that precise delivery of CO to isolated heart mitochondria using a water-soluble CO-releasing molecule (CORM-3) uncouples respiration. Addition of low-micromolar concentrations of CORM-3 (1-20 μM), but not an inactive compound that does not release CO, significantly increased mitochondrial oxygen consumption rate (State 2 respiration) in a concentration-dependent manner. In contrast, higher concentrations of CORM-3 (100 μM) suppressed ADP-dependent respiration through inhibition of cytochrome c oxidase. The uncoupling effect mediated by CORM-3 was inhibited in the presence of the CO scavenger myoglobin. Moreover, this effect was associated with a gradual decrease in membrane potential (ψ) over time and was partially reversed by malonate, an inhibitor of complex II activity. Similarly, inhibition of uncoupling proteins or blockade of adenine nucleotide transporter attenuated the effect of CORM-3 on both State 2 respiration and Δψ. Hydrogen peroxide (H₂O₂) produced by mitochondria respiring from complex I-linked substrates (pyruvate/malate) was increased by CORM-3. However, respiration initiated via complex II using succinate resulted in a fivefold increase in H₂O₂ production and this effect was significantly inhibited by CORM-3. These findings disclose a counterintuitive action of CORM-3 suggesting that CO at low levels acts as an important regulator of mitochondrial respiration.
authors.affiliation: Department of Drug Discovery and Development, Italian Institute of Technology, 16163 Genoa, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Lo Iacono
authors.forename: Jorge
authors.initials: J
authors.lastname: Boczkowski
authors.forename: Roland
authors.initials: R
authors.lastname: Zini
authors.forename: Issam
authors.initials: I
authors.lastname: Salouage
authors.forename: Alain
authors.initials: A
authors.lastname: Berdeaux
authors.forename: Roberto
authors.initials: R
authors.lastname: Motterlini
authors.forename: Didier
authors.initials: D
authors.lastname: Morin
mesh_terms: D000818:Animals; D002248:Carbon Monoxide / Q000737:chemistry / Q000378:metabolism*; D019069:Cell Respiration / Q000187:drug effects; D042963:Electron Transport Complex II / Q000378:metabolism*; D006321:Heart / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000378:metabolism; D008297:Male; D053078:Membrane Potential, Mitochondrial; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism*; D009942:Organometallic Compounds / Q000737:chemistry / Q000494:pharmacology*; D058451:Oxidative Coupling / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D009942:Organometallic Compounds; D017382:Reactive Oxygen Species; C476530:tricarbonylchloro(glycinato)ruthenium(II); D002248:Carbon Monoxide; D006861:Hydrogen Peroxide; D042963:Electron Transport Complex II